Liquid dispensing device and control method for liquid dispensing device

Abstract

In a liquid dispensing device, the time required to detect dispensing abnormalities in multiple dispensing sections, each including a nozzle, is shortened. [Solution] The liquid dispensing device performs a first operation in which a drive unit simultaneously applies a drive voltage to a group of interest, which is one of a plurality of groups each containing a predetermined number of piezoelectric elements, and a selection unit simultaneously selects a plurality of voltage lines corresponding to the group of interest, and if an abnormality determination unit determines that there is an abnormality in the residual vibration data appearing on the plurality of selected voltage lines, it detects that there is a dispensing abnormality in one of the plurality of dispensing units corresponding to the group of interest; and if a dispensing abnormality is detected in the first operation, the drive unit sequentially applies a drive voltage to a plurality of piezoelectric elements within the group of interest, the selection unit sequentially selects the voltage lines to which the drive voltage has been applied, and the selection unit detects that there is a dispensing abnormality in the dispensing unit corresponding to the piezoelectric element for which an abnormality in the residual vibration data has been determined.

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection apparatus and a control method for a liquid ejection apparatus. [Background Art]

[0002] A liquid ejection apparatus such as an inkjet printer applies a drive signal to a head mounted with a drive element such as a piezoelectric element, and ejects ink droplets from nozzles provided in an inkjet recording head to print an image on paper or the like. Specifically, driving the drive element causes a pressure change in ink inside a pressure chamber provided in the inkjet recording head, whereby ink droplets are ejected from a nozzle communicating with the pressure chamber.

[0003] In this type of liquid ejection apparatus, if evaporation of the ink solvent from a nozzle increases the viscosity of ink inside the nozzle, or if air bubbles enter the inside of the nozzle, ink ejection failure from the nozzle may occur. Accordingly, a technique is known that inspects defective nozzles in which ejection failure occurs, on the basis of residual vibration that appears after a pressure change is caused in ink inside a pressure chamber by driving of a drive element (see, for example, Patent Document 1).

[0004] Furthermore, when detecting ink ejection failure from nozzles on the basis of residual vibration, a technique is known that shortens the detection time of residual vibration by overlapping a part of detection pulses used for detecting residual vibration of a plurality of nozzles within one cycle of a detection drive waveform (see, for example, Patent Document 2). [Summary of Invention] [Problem to be Solved by the Invention]

[0005] When detecting residual vibration for each nozzle by sequentially driving a plurality of nozzles in order to detect ink ejection failure from nozzles, there is a problem in that the detection time of residual vibration becomes longer depending on the number of nozzles.

[0006] The disclosed technology was developed in view of the above-mentioned problems and aims to shorten the time required to determine abnormalities in discharge sections, including nozzles, in a liquid dispensing device. [Means for solving the problem]

[0007] To solve the above technical problems, one embodiment of the present invention provides a liquid dispensing device comprising: a plurality of piezoelectric elements that apply pressure to a plurality of dispensing sections, each including a nozzle for dispensing liquid; a plurality of voltage lines connected to the plurality of piezoelectric elements; a drive unit that applies a drive voltage to the plurality of piezoelectric elements via the plurality of voltage lines; a selection unit that selects one or more of the voltage lines after the application of the drive voltage to the plurality of piezoelectric elements and generates residual vibration data based on the sum of residual vibration voltages due to residual vibration appearing on the selected voltage lines; an abnormality determination unit that determines an abnormality in the residual vibration data by comparing the residual vibration data generated by the selection unit with a reference value for determining an abnormality in residual vibration; and a control unit that detects the dispensing section having a dispensing abnormality based on the determination result by the abnormality determination unit, wherein the control unit comprises a predetermined number The invention is characterized by performing a first operation in which the drive unit simultaneously applies a drive voltage to a group of interest, which is one of a plurality of groups each containing the piezoelectric elements, and the selection unit simultaneously selects a plurality of voltage lines corresponding to the group of interest, and if the abnormality determination unit determines that there is an abnormality in the residual vibration data appearing on the plurality of selected voltage lines, it detects that there is a discharge abnormality in one of the plurality of discharge units corresponding to the group of interest; and if a discharge abnormality is detected in the first operation, the drive unit sequentially applies a drive voltage to a plurality of piezoelectric elements within the group of interest, the selection unit sequentially selects the voltage lines to which the drive voltage has been applied, and the selection unit detects that there is a discharge abnormality in the discharge unit corresponding to the piezoelectric element for which an abnormality in the residual vibration data has been determined. [Effects of the Invention]

[0008] In a liquid dispensing device, the time required to detect dispensing abnormalities in multiple dispensing sections, each including a nozzle, can be shortened. [Brief explanation of the drawing]

[0009] [Figure 1] This is a block diagram showing a first embodiment of a liquid dispensing device according to the present invention. [Figure 2] Figure 1 is a schematic side view showing an example of an inkjet recording head module mounted on an inkjet recording device. [Figure 3] This figure shows an example of a nozzle plate provided on the bottom surface of the inkjet recording head shown in Figure 2. [Figure 4] Figure 2 is a block diagram showing an example of the circuitry mounted on an inkjet recording head. [Figure 5] Figure 4 is a block diagram illustrating the circuit configuration of the drive unit and the selection unit. [Figure 6] This timing diagram illustrates the difference in residual vibration voltage waveforms with and without the switch shown in Figure 5. [Figure 7] This block diagram shows an overview of the selection, comparison, and data storage sections in Figure 4. [Figure 8] This timing diagram shows examples of residual vibration waveforms corresponding to the number of residual vibration voltages selected by the selection unit in Figure 4. [Figure 9] Figure 4 is a flowchart illustrating an example of the initial operations performed before detecting a nozzle ejection abnormality by the inkjet recording head. [Figure 10] Figure 4 is a flowchart illustrating an example of the operation for detecting nozzle ejection abnormalities by the inkjet recording head. [Figure 11] This flowchart shows an example of the operation for detecting nozzle ejection abnormalities by an inkjet recording head in a second embodiment of the liquid ejection device according to the present invention. [Figure 12] Figure 4 is a block diagram showing an example of the hardware configuration of an inkjet recording head. [Modes for carrying out the invention]

[0010] The embodiments will be described below with reference to the drawings. In each drawing, the same components are denoted by the same reference numerals, and redundant explanations may be omitted. Also, the numerals indicating signals may be used to indicate signal lines, signal terminals, or signal nodes.

[0011] Here, a liquid dispensing device is a device that dispenses liquid, comprising a liquid dispensing head or liquid dispensing unit, and dispensing liquid by driving the liquid dispensing head. Liquid dispensing devices include not only devices that can dispense liquid onto surfaces to which liquid can adhere, but also devices that dispense liquid into air or into liquid. For example, devices that incorporate liquid dispensing devices include image forming apparatuses, 3D modeling apparatuses, processing liquid coating apparatuses, or spray granulation apparatuses. A processing liquid coating apparatus may be mounted on an electrode manufacturing apparatus.

[0012] The liquid dispensing device may also include means for feeding, transporting, and dispensing paper onto materials to which liquid can adhere, as well as pre-treatment devices, post-treatment devices, etc.

[0013] For example, devices equipped with liquid ejection devices include image forming machines, which eject ink to form images on paper, and three-dimensional molding machines, which eject molding liquid onto a powder layer formed in layers to create three-dimensional objects.

[0014] Furthermore, the liquid dispensing device is not limited to a device that visualizes meaningful images such as letters or figures using the dispensed liquid. For example, the liquid dispensing device may be a device that forms meaningless patterns, or a device that creates three-dimensional images.

[0015] The term "materials to which liquid can adhere" above refers to materials to which liquid can adhere, at least temporarily, including materials that adhere and solidify, or materials that adhere and penetrate. Specific examples include recording media such as paper, recording paper, film, and cloth; electronic components such as electronic circuit boards and piezoelectric elements; powder layers; organ models; and inspection cells. Unless otherwise specified, it includes all materials to which liquid can adhere.

[0016] The material of the aforementioned "object to which liquid can adhere" is not particularly limited as long as liquid can adhere thereto even temporarily, and examples thereof include paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, and ceramics.

[0017] Further, the "liquid" is not particularly limited as long as it has viscosity and surface tension that allow it to be discharged from a head. It is preferable that the viscosity of the "liquid" is 30 mPa·s or less at normal temperature and normal pressure, or when heated or cooled. More specifically, the "liquid" includes solutions, suspensions, emulsions and the like containing: solvents such as water and organic solvents; colorants such as dyes and pigments; functional-imparting materials such as polymerizable compounds, resins and surfactants; biocompatible materials such as DNA, amino acids, proteins and calcium; and edible materials such as natural pigments. These liquids can be used in applications such as inkjet inks, surface treatment liquids, liquids for forming components of electronic elements and light-emitting elements or for forming electronic circuit resist patterns, and material liquids for three-dimensional modeling, for example.

[0018] Further, although there exist liquid ejection apparatuses in which the liquid ejection head and the object to which liquid can adhere move relatively to each other, the liquid ejection apparatus is not limited thereto. Specific examples of the liquid ejection apparatus include a serial type apparatus that moves the liquid ejection head and a line type apparatus that does not move the liquid ejection head.

[0019] Further, in addition to those described above, examples of the liquid ejection apparatus include: a treatment liquid coating apparatus that ejects a treatment liquid onto paper for the purpose of modifying the surface of the paper to coat the surface of the paper with the treatment liquid; and a jet granulation apparatus that jets a composition liquid, in which raw materials are dispersed in a solution, through a nozzle to granulate fine particles of the raw materials.

[0020] Hereinafter, an embodiment will be described by taking, as an example, a case where the "object to which liquid can adhere" is a sheet material, and the liquid ejection apparatus is mounted on a line scanning type inkjet image forming apparatus.

[0021] (First Embodiment of Liquid Ejection Apparatus) Figure 1 is a block diagram showing a first embodiment of the liquid ejection device according to the present invention. As an example of a liquid ejection device, Figure 1 shows a schematic configuration diagram of a line scanning type inkjet recording device 100 in an on-demand system according to this embodiment.

[0022] As shown in Figure 1, the inkjet recording apparatus 100 is positioned between the recording medium supply unit 111 and the recording medium retrieval unit 112, and includes a recording means 101, a platen 102 provided opposite the recording means 101, a drying means 103, a maintenance and recovery means 114, a recording medium transport device, and the like.

[0023] The recording medium transport device includes a regulating guide 104, an infeed section 105, a dancer roller 106, an EPC (Edge Position Control) 107, a meandering amount detector 108, an outfeed section 109, a puller 110, etc. Continuous recording media (also called roll paper, continuous paper, etc.) 113 are fed out at high speed from the recording medium supply section 111 and wound up and recovered by the recording medium recovery section 112.

[0024] (Inkjet recording head module) Figure 2 is a schematic side view showing an example of an inkjet recording head module mounted on the inkjet recording device 100 shown in Figure 1. As shown in Figure 2, the inkjet recording device 100 includes a drive control board 210, an inkjet recording head 220, and a cable 230, etc.

[0025] The drive control board 210 is equipped with a controller 211, a drive waveform generation unit 212, a storage means 213, etc. The inkjet recording head 220 includes a head board 221, a residual vibration detection board 222, a head drive IC board 223, an ink tank 224, and a rigid plate 225, etc. The cable 230 is connected to the drive control board side connector 231 and the head side connector 232, and transmits analog and digital signals between the drive control board 210 and the head board 221.

[0026] The line-scanning inkjet recording device 100 may have one or more inkjet recording heads 220 arranged perpendicular to the transport direction of the recording medium 113 to which liquid droplets (ink) are attached. The inkjet recording head 220 is provided with multiple nozzles arranged in rows along the width direction of the recording medium 113, corresponding to the width of the recording medium 113. The rows of nozzles may be one row or multiple rows. By ejecting liquid droplets onto the recording medium 113 from the rows of nozzles on the inkjet recording head 220, high-speed image formation becomes possible.

[0027] Furthermore, the droplet ejection device according to this embodiment can also be applied to serial scanning inkjet recording devices and the like, which form an image by moving one or more inkjet recording heads in a direction perpendicular to the transport direction of the recording medium 113.

[0028] (Example of a nozzle plate) Figure 3 shows an example of a nozzle plate 226 provided on the bottom surface of the inkjet recording head 220 shown in Figure 2. The nozzle plate 226 shown in Figure 3 has a plurality of nozzles 227 (nozzle rows) arranged in four rows perpendicular to the transport direction of the recording medium 113. For example, each nozzle row has a number of nozzles 227 that is a multiple of 8, and 8 nozzles 227 are assigned to one nozzle block. The ejection section is formed by each nozzle 227 and a pressure chamber (not shown) provided corresponding to each nozzle 227. Hereinafter, an ejection abnormality in the ejection section will also be referred to as an ejection abnormality of the nozzle 227. Note that the number of rows provided on the nozzle plate 226 and the number of nozzles 227 included in each nozzle block are not limited to those described above. Nozzle blocks are provided corresponding to groups containing a predetermined number of piezoelectric elements.

[0029] (Circuits installed in the inkjet recording head) Figure 4 is a block diagram showing an example of a circuit mounted on the inkjet recording head 220 shown in Figure 2. The inkjet recording head 220 includes a drive control unit 10, a drive unit 20, a plurality of piezoelectric elements 30, a selection unit 40, a comparison unit 50, a determination unit 60, and a data holding unit 70. For example, the drive control unit 10, the drive unit 20, the plurality of piezoelectric elements 30, the selection unit 40, the comparison unit 50, the determination unit 60, and the data holding unit 70 are formed by circuits.

[0030] Furthermore, some functions of the drive control unit 10 may be implemented by a processor such as a CPU. In this case, the comparison unit 50 and the determination unit 60 may be implemented by a control program executed by the processor. Also, the data holding unit 70 may be allocated to an internal memory mounted on the processor or to memory accessed by the processor.

[0031] The drive control unit 10 receives print signals, operation instruction signals, etc., from the controller 211. For example, the controller 211 is a processor such as a CPU. The controller 211 controls the overall operation of the inkjet recording device 100, but may also control only the operation of the inkjet recording head 220. In this case, the controller 211 may be located within the inkjet recording head 220 or may be included in the drive control unit 10. The drive control unit 10 and the controller 211 are examples of control units.

[0032] For example, the printing signal includes information indicating the size of the droplet ejected from each nozzle 227 shown in Figure 3. This allows a grayscale image corresponding to the droplet size to be formed on the recording medium 113 shown in Figure 2. For example, the operation instruction signal includes information indicating the nozzle row that ejects droplets, information indicating the piezoelectric element 30 (i.e., the driving voltage) to be selected by the selection unit 40, and information instructing flushing for the nozzle 227 in which an abnormal residual vibration has been detected. For example, an abnormal residual vibration occurs when the ink inside the nozzle 227 becomes thicker due to evaporation of the ink solvent from the nozzle 227, or when air bubbles are mixed into the nozzle.

[0033] The drive control unit 10 outputs a drive signal to the drive unit 20 and a nozzle selection signal to the drive unit 20 and the selection unit 40 based on instructions from the controller 211. The drive signal includes information for driving each piezoelectric element 30. The nozzle selection signal is output for each nozzle 227 and is set to an effective level (e.g., high level) when residual vibration of the piezoelectric element 30 corresponding to the nozzle 227 that ejects droplets is detected, and to an ineffective level (e.g., low level) when residual vibration of the piezoelectric element 30 is not detected.

[0034] The drive unit 20 outputs a drive voltage to the piezoelectric element 30 corresponding to the nozzle 227 that discharges liquid, based on the drive signal and nozzle selection signal received from the drive control unit 10. Multiple piezoelectric elements 30 are provided corresponding to the nozzles 227 provided on the nozzle plate 226 in Figure 3. An example of the drive unit 20 is shown in Figure 5. Each piezoelectric element 30 operates according to its corresponding drive voltage, causing the nozzle 227 to discharge liquid droplets.

[0035] The selection unit 40 selects one or more drive voltage lines to be used for detecting residual vibration based on the nozzle selection signal received from the drive control unit 10, converts the voltage values ​​of the selected drive voltage lines into comparable digital data by the comparison unit 50, and outputs them to the comparison unit 50 as residual vibration data. Note that the more drive voltage lines selected, the larger the total voltage values ​​input to the selection unit 40. Examples of the selection unit 40 are shown in Figures 5 and 7.

[0036] The comparison unit 50 compares the residual vibration data value with a reference value held in the data holding unit 70 and outputs the difference data to the determination unit 60. An example of the comparison unit 50 is shown in Figure 7.

[0037] The determination unit 60 determines whether or not there is an abnormality in the residual vibration data based on the difference data from the comparison unit 50. An abnormality in the residual vibration data indicates whether or not there is a possibility of a discharge abnormality in the nozzle 227 corresponding to the piezoelectric element 30 that generated the residual vibration voltage selected by the selection unit 40. The determination unit 60 outputs the determination result to the controller 211 and stores the determination result in the data holding unit 70. For example, the determination result includes information indicating the nozzle row or nozzle block to be judged for discharge abnormality and information indicating that an abnormality in the residual vibration data has been determined. The comparison unit 50 and the determination unit 60 are an example of an abnormality determination unit that determines an abnormality in residual vibration data by comparing the residual vibration data with a reference value for determining the abnormality of residual vibration.

[0038] The data holding unit 70 includes a reference value holding unit that holds reference values ​​used by the comparison unit 50, and a judgment result holding unit that holds the judgment results from the judgment unit 60. Based on the reference value readout signal received from the controller 211, the data holding unit 70 reads reference values ​​from the reference value holding unit and outputs them to the comparison unit 50. An example of the data holding unit 70 is shown in Figure 7.

[0039] (Overview of the circuit configuration of the drive unit and selection unit) Figure 5 is a diagram showing an overview of the circuit configuration of the drive unit 20 and the selection unit 40 shown in Figure 4. The drive unit 20 is provided in correspondence with the piezoelectric element 30. The drive unit 20 includes a driver DRV that generates a drive voltage in response to a drive signal from the drive control unit 10, and a switch SW1 that is positioned between the driver DRV and the piezoelectric element 30 and operates in response to the drive signal and the nozzle selection signal. Switch SW1 is an example of a first switch.

[0040] Switch SW1 operates based on the NAND logic of the drive signal logic and the nozzle selection signal logic. For example, switch SW1 turns on when the drive signal is set to a low level and a drive voltage is applied to the piezoelectric element 30, and turns off when the nozzle selection signal is set to a high level to detect residual vibration. The low-level period of the drive signal and the high-level period of the nozzle selection signal are set mutually exclusive. The drive control unit 10 in Figure 4 generates a nozzle selection signal for each piezoelectric element 30.

[0041] The selection unit 40 includes an ADC (Analog-to-Digital Converter) that converts an analog drive voltage into digital residual vibration data, and a switch SW2 positioned between the piezoelectric element 30 and the ADC, which operates according to the nozzle selection signal. For example, the switch SW2 is turned on when the nozzle selection signal is set to a high level to detect residual vibration, and turned off when the nozzle selection signal is set to a low level.

[0042] Although the selection unit 40 shown in Figure 5 has only one switch SW2 connected to one piezoelectric element 30, in reality, it has multiple switches SW2 connected to multiple piezoelectric elements 30 corresponding to multiple nozzles 227 included in the nozzle row. The ADC then generates digital residual vibration data that shows the change in one or more residual vibration voltages supplied via the switch SW2 that is turned on in response to the nozzle selection signal.

[0043] During the period when the drive control unit 10 drives the piezoelectric element 30, switch SW1 is turned on and a drive voltage is applied to the piezoelectric element 30. At this time, switch SW2 is turned off, so the ADC does not output residual vibration data. After the piezoelectric element 30 has been driven, when the nozzle selection signal is temporarily set to a high level, switch SW2 is turned on. As a result, the ADC converts the voltage value of the residual vibration voltage due to the back electromotive force from the piezoelectric element 30 into digital data and outputs it as residual vibration data.

[0044] (Differences in residual vibration voltage waveform depending on the presence or absence of a switch) Figure 6 is a timing diagram illustrating the difference in residual vibration voltage waveforms depending on the presence or absence of switches SW1 and SW2 in Figure 5. When switches SW1 and SW2 are not installed in the drive unit 20 and the selection unit 40, the load, such as the output capacitance of the driver DRV of the drive unit 20, is connected to the drive voltage line.

[0045] Therefore, if the drive unit 20 does not have a switch SW1, the change in residual vibration voltage due to residual vibration that occurs after the application of the drive voltage to the piezoelectric element 30 will hardly appear on the drive voltage line, making it difficult to generate residual vibration data corresponding to the residual vibration voltage using the ADC. Also, if the selection unit 40 does not have a switch SW2, the residual vibration voltage from all piezoelectric elements 30 will be input to the ADC. Furthermore, when the drive voltage is applied to the piezoelectric element 30, a portion of the drive voltage may be input to the ADC of the selection unit 40, potentially preventing the desired drive voltage from being applied to the piezoelectric element 30.

[0046] On the other hand, if switches SW1 and SW2 are mounted on the drive unit 20 and the selection unit 40 respectively, after the drive voltage is applied to the piezoelectric element 30, the load such as the output capacitance of the driver DRV is not connected to the drive voltage line by turning off switch SW1. Therefore, the change in residual vibration voltage due to residual vibration can be greatly increased. In addition, the number of residual vibration voltages input to the ADC can be controlled according to the nozzle selection signal. Furthermore, by turning off switch SW2, it is possible to suppress the input of the drive voltage to the ADC when the drive voltage is applied to the piezoelectric element 30.

[0047] (Overview of the selection, comparison, and data storage sections) Figure 7 is a block diagram showing an overview of the selection unit 40, comparison unit 50, and data holding unit 70 of Figure 4. The selection unit 40 further includes a smoothing unit 41, a peak detection unit 42, and a phase detection unit 43 connected to the output of the ADC in Figure 6. The comparison unit 50 includes difference generation units 51, 52, and 53. The data holding unit 70 includes a reference value holding unit 71 and a judgment result holding unit 72.

[0048] The selection unit 40 may have at least one of the smoothing unit 41, the peak detection unit 42, and the phase detection unit 43. In this case, the comparison unit 50 has a difference generation unit corresponding to the smoothing unit 41, the peak detection unit 42, or the phase detection unit 43 mounted on the selection unit 40. The smoothing unit 41, the peak detection unit 42, and the phase detection unit 43 may be arranged between the selection unit 40 and the comparison unit 50, or they may be arranged within the comparison unit 50.

[0049] The selection unit 40 operates one of the smoothing unit 41, peak detection unit 42, or phase detection unit 43 in response to a selection signal from the controller 211. The comparison unit 50 operates one of the difference generation units (51, 52, or 53) corresponding to the operating smoothing unit 41, peak detection unit 42, or phase detection unit 43 in response to a selection signal from the controller 211.

[0050] The smoothing unit 41 smooths the voltage amplitude of the residual vibration data output from the ADC to obtain smoothed data, which is then output to the comparison unit 50. The peak detection unit 42 obtains the peak values ​​(maximum and minimum values) of the amplitude of the voltage waveform of the residual vibration data output from the ADC, calculates the voltage amplitude Vp-p between the peaks, and outputs it to the comparison unit 50. The phase detection unit 43 obtains the phase or period in which the peak value of the amplitude of the voltage waveform of the residual vibration data output from the ADC appears, and outputs it to the comparison unit 50.

[0051] The difference generation unit 51 compares the voltage value of the smoothed data acquired by the smoothing unit 41 with the reference value of the smoothed data read from the reference value holding unit 71, and outputs the difference between the voltage value of the smoothed data and the reference value as difference data. The difference generation unit 52 compares the voltage amplitude Vp-p value acquired by the peak detection unit 42 with the reference value of the voltage amplitude read from the reference value holding unit 71, and outputs the difference between the voltage amplitude Vp-p value and the reference value as difference data. The difference generation unit 53 compares the value indicating the phase or period acquired by the phase detection unit 43 with the reference value of the phase or period read from the reference value holding unit 71, and outputs the difference between the value indicating the phase or period and the reference value as difference data.

[0052] The reference value holding unit 71 holds reference values ​​corresponding to the number of nozzles in a nozzle row, the number of nozzles in a nozzle block, and a single nozzle, respectively, corresponding to the voltage value output from the smoothing unit 41, the voltage amplitude Vp-p value output from the peak detection unit 42, and the value indicating the phase or period output from the phase detection unit 43. For example, the reference values ​​are determined by evaluations performed during the development of the inkjet recording device 100.

[0053] The determination result holding unit 72 holds the determination results from the determination unit 60. For example, the determination result holding unit 72 holds frequency information as a determination result, which indicates the frequency of occurrence of anomalies, such as the number of nozzle blocks or nozzles in which anomalies in residual vibration data were detected. The determination result holding unit 72 also holds a reference frequency (number of nozzle blocks or number of nozzles) for determining whether the frequency of anomalies is high or low.

[0054] (Example of residual vibration data corresponding to the number of residual vibration voltages) Figure 8 is a timing diagram showing an example of residual vibration data corresponding to the number of residual vibration voltages selected by the selection unit 40 in Figure 4. For example, the selection unit 40 generates residual vibration data by converting the voltage values ​​of residual vibration data corresponding to nozzles 227 included in one nozzle row, residual vibration data corresponding to nozzles 227 included in one nozzle block, or residual vibration voltages corresponding to one nozzle 227 into digital values.

[0055] The more residual vibration voltages generated by the residual vibration data, the larger the signal amount of the residual vibration voltage input to the ADC, and the larger the amplitude of the residual vibration data waveform. The comparison unit 50 then compares the residual vibration data generated according to the number of residual vibration voltages with a reference value corresponding to the number of residual vibration voltages and outputs difference data. The comparison unit 50 can correctly determine discharge abnormalities by comparing residual vibration data with different amplitudes according to the number of residual vibration voltages with a reference value that also differs according to the number of residual vibration voltages. In Figure 8, an example is shown in which a nozzle selection signal is generated twice in one discharge cycle T, generating two residual vibration data. However, if the discharge cycle T can be made even larger, three or more residual vibration data may be generated.

[0056] (Initial operation of the inkjet recording head) Figure 9 is a flowchart showing an example of initial operations performed before detecting an ejection abnormality of the nozzle 227 by the inkjet recording head 220 shown in Figure 4. For example, the operations shown in Figure 9 are performed by the controller 211 when the inkjet recording device 100 is started up.

[0057] First, in step S10, the controller 211 reads a reference value from the data holding unit 70. Next, in step S12, the controller 211 sets the reference value read from the data holding unit 70 into the buffer or register of the comparison unit 50, and terminates the operation shown in Figure 9.

[0058] (Operation flow for detecting nozzle discharge abnormalities) Figure 10 is a flowchart illustrating an example of the operation for detecting an ejection abnormality of the nozzle 227 by the inkjet recording head 220 shown in Figure 4. For example, the flow shown in Figure 10 is performed when the inkjet recording device 100 is started up, before or after the inkjet recording head 220 ejects droplets onto the recording medium 113. Note that the flow shown in Figure 10 may also be performed while the inkjet recording head 220 is ejecting droplets onto the recording medium 113, with the ejection temporarily interrupted.

[0059] First, in step S20, the drive control unit 10 is activated to dispense droplets in response to instructions from the controller 211. In steps S22 to S28, it is detected whether there is a dispensing abnormality in at least one of the nozzles 227 included in one nozzle row. If there are multiple nozzle rows on the nozzle plate 226, the operation in steps S22 to S28 may be repeated for each nozzle row. The operation in steps S22 to S28 is an example of a third operation.

[0060] Following step S20, in step S22, the drive control unit 10 simultaneously applies a drive voltage to the piezoelectric elements 30 corresponding to all nozzles 227 included in one nozzle row. The selection unit 40 simultaneously acquires a plurality of residual vibration voltages generated in accordance with the drive voltage applied to the piezoelectric elements 30 corresponding to all nozzles 227 included in one nozzle row, and generates residual vibration data corresponding to the sum of the residual vibration voltages.

[0061] Next, in step S24, the comparison unit 50 compares the residual vibration data generated by the selection unit 40 with a reference value for detecting discharge abnormalities in the nozzle row, and outputs the comparison result as difference data to the determination unit 60. Next, in step S26, the determination unit 60 determines whether or not there is an abnormality in the residual vibration data (i.e., residual vibration waveform and residual vibration voltage) based on the difference data.

[0062] If there is an abnormality in the residual vibration data, the operation proceeds to step S28. If there is no abnormality in the residual vibration data, the nozzle 227 discharge abnormality detection operation is terminated because there are no discharge abnormalities in any of the nozzles 227 in the nozzle row targeted for abnormality detection. In other words, if there is no abnormality in the residual vibration data in step S26, the discharge abnormality detection operation can be terminated by skipping the determination of discharge abnormalities for each nozzle 227.

[0063] In step S28, the determination unit 60 stores information indicating the nozzle row subject to discharge abnormality determination and information indicating that an abnormality in residual vibration data has been determined as determination results in the determination result holding unit 72 of the data holding unit 70. In other words, the occurrence history of abnormalities in the residual vibration data of the nozzle row subject to discharge abnormality determination is stored in the determination result holding unit 72.

[0064] After step S28, steps S30 to S36 are performed. In steps S30 to S36, it is detected whether there is a discharge abnormality in at least one of the nozzles 227 included in each of the multiple nozzle blocks included in the nozzle row in which an abnormality in the residual vibration waveform was detected. The operation of steps S30 to S36 is repeated for the number of nozzle blocks included in the nozzle row in which an abnormality in the residual vibration data was detected. The operation of steps S30 to S36 is an example of the first operation.

[0065] First, in step S30, the drive control unit 10 simultaneously applies a drive voltage to the piezoelectric elements 30 corresponding to all nozzles 227 in one of the multiple nozzle blocks in the nozzle row in which an anomaly in the residual vibration data was detected. The selection unit 40 simultaneously acquires multiple residual vibration voltages generated in accordance with the drive voltage applied to the piezoelectric elements 30 corresponding to all nozzles 227 in one nozzle block in the nozzle row in which an anomaly in the residual vibration data was detected, and generates residual vibration data.

[0066] Next, in step S32, the comparison unit 50 compares the residual vibration data generated by the selection unit 40 with a reference value for detecting discharge abnormalities in the nozzle block and outputs the comparison result as difference data to the determination unit 60. Next, in step S34, the determination unit 60 detects nozzle blocks with abnormal residual vibration data (i.e., residual vibration waveform and residual vibration voltage) as nozzle blocks with discharge abnormalities based on the difference data. Next, in step S36, the determination unit 60 stores information indicating the nozzle block in which an abnormality was detected as a determination result in the determination result holding unit 72 of the data holding unit 70. That is, the occurrence history of abnormalities in the residual vibration data of the nozzle block, including the nozzle 227 with a discharge abnormality, is stored in the determination result holding unit 72.

[0067] After step S36, steps S40 to S46 are performed. In steps S40 to S46, among the multiple nozzles 227 included in the nozzle block in which an abnormality in residual vibration data was detected, the nozzle 227 with a discharge abnormality is detected. The operation from steps S30 to S36 is repeated for the number of nozzles 227 included in the nozzle block in which a discharge abnormality was detected. The operation from steps S40 to S46 is an example of the second operation.

[0068] First, in step S40, the drive control unit 10 applies a drive voltage to a piezoelectric element 30 corresponding to one of the multiple nozzles 227 included in the nozzle block in which an abnormality in residual vibration data was detected. The selection unit 40 acquires the residual vibration voltage generated in accordance with the drive voltage applied to the piezoelectric element 30 corresponding to one of the nozzles 227 in the nozzle block in which an abnormality in residual vibration data was detected, and generates residual vibration data.

[0069] Next, in step S42, the comparison unit 50 compares the residual vibration data generated by the selection unit 40 with a reference value for detecting discharge abnormalities in the nozzle 227 and outputs the comparison result as difference data to the determination unit 60. Next, in step S44, the determination unit 60 detects nozzles 227 with abnormal residual vibration data (i.e., residual vibration waveform and residual vibration voltage) based on the difference data as nozzles 227 with discharge abnormalities. Next, in step S46, the determination unit 60 stores information indicating the nozzle 227 that has been detected to have a discharge abnormality as a determination result in the determination result holding unit 72 of the data holding unit 70. That is, the occurrence history of nozzles 227 that have experienced discharge abnormalities is stored in the determination result holding unit 72. Then, since nozzles 227 with discharge abnormalities have been detected, the operation shown in Figure 10 is terminated.

[0070] In the first embodiment described above, the controller 211 detects whether there is a discharge abnormality in at least one of the nozzles 227 included in each of the multiple nozzle blocks included in a single nozzle row, and detects the nozzle 227 with the discharge abnormality from among the multiple nozzles 227 included in the nozzle block in which the discharge abnormality was detected. As a result, it is no longer necessary to detect whether there is a discharge abnormality for each nozzle 227 included in the nozzle row, and the determination time for determining whether there is a discharge abnormality in a nozzle 227 can be shortened.

[0071] By varying the reference value depending on whether the residual vibration data abnormality is checked on a nozzle row basis, a nozzle block basis, or a nozzle basis, discharge abnormalities can be correctly determined. Before detecting whether or not there is a residual vibration data abnormality for each nozzle block, the determination time for determining whether or not there is a discharge abnormality in nozzle 227 can be further shortened by detecting whether or not there is a residual vibration data abnormality for each nozzle row containing multiple nozzle blocks.

[0072] By turning off switch SW1 after the drive voltage is applied to the piezoelectric element 30, the load such as the output capacitance of the driver DRV is prevented from being connected to the drive voltage line, thereby increasing the change in residual vibration voltage due to residual vibration. Furthermore, by turning off switch SW2, the drive voltage is prevented from being input to the ADC when the drive voltage is applied to the piezoelectric element 30.

[0073] The comparison unit 50 smooths the voltage amplitude of the residual vibration data and generates difference data by comparing the smoothed data, the peak value of the amplitude of the voltage waveform of the residual vibration data, or the phase or period of the peak value of the voltage waveform of the residual vibration data with the corresponding reference value. This makes it possible to selectively use various characteristic values ​​obtained from the residual vibration data to detect whether or not there is an abnormality in the discharge.

[0074] <Second Embodiment of Liquid Dispensing Device> Figure 11 is a flowchart showing an example of the operation for detecting an ejection abnormality of the nozzle 227 by the inkjet recording head 220 in a second embodiment of the liquid ejection device according to the present invention. For example, the flow shown in Figure 11 is performed when the inkjet recording device 100 is started up, before or after the inkjet recording head 220 ejects droplets onto the recording medium 113. Note that the flow shown in Figure 11 may also be performed while the inkjet recording head 220 is ejecting droplets onto the recording medium 113, with the ejection temporarily interrupted.

[0075] The configuration of the liquid dispensing device in the second embodiment is the same as in Figures 1 to 5 and 7, and the basic operation of the liquid dispensing device in the second embodiment is the same as in Figures 6, 8 and 9. The operation shown in Figure 11 is performed before the operation shown in Figure 10, depending on the frequency of abnormalities. If there are multiple nozzle blocks with a high frequency of residual vibration abnormalities, the operation from step S52 to step S66 is performed for each nozzle block.

[0076] First, in step S50, the drive control unit 10 is activated in response to an instruction from the controller 211 to discharge droplets. After step S50, steps S52 to S58 are performed. In steps S52 to S58, it is detected whether there is a discharge abnormality in at least one of the nozzles 227 of the nozzle block, where residual vibration abnormalities occur frequently. The operation in steps S52 to S58 is an example of the fourth operation.

[0077] In step S52, the drive control unit 10 simultaneously applies a drive voltage to all piezoelectric elements 30 corresponding to all nozzles 227 included in one of the nozzle blocks in which abnormalities in residual vibration data are frequently detected, based on the history of abnormalities in residual vibration data of the nozzle block held in the determination result holding unit 72. The selection unit 40 simultaneously acquires a plurality of residual vibration voltages generated in accordance with the drive voltage applied to the piezoelectric elements 30 corresponding to all nozzles 227 included in one of the nozzle blocks in which abnormalities in residual vibration data are frequently detected, and generates residual vibration data.

[0078] Next, in step S54, the comparison unit 50 compares the residual vibration data generated by the selection unit 40 with a reference value for detecting discharge abnormalities in the nozzle block, and outputs the comparison result as difference data to the determination unit 60. Next, in step S56, the determination unit 60 determines whether or not there is an abnormality in the residual vibration data (i.e., residual vibration waveform and residual vibration voltage) based on the difference data. If there is an abnormality in the residual vibration data, the operation proceeds to step S58.

[0079] If there are no abnormalities in the residual vibration data, all nozzles 227 in the nozzle block targeted for abnormality detection are free from discharge abnormalities. However, there is a possibility that one of the nozzles 227 in the other nozzle blocks not targeted for abnormality detection may have a discharge abnormality. Therefore, the process proceeds to step S22 in Figure 10 of the first embodiment. Note that the other nozzle blocks not targeted for abnormality detection have a low frequency of residual vibration abnormalities, so they are likely to be determined to be free of abnormalities in step S26 of Figure 10.

[0080] In step S58, the determination unit 60 stores information indicating the nozzle block in which an abnormality was detected as a determination result in the determination result holding unit 72 of the data holding unit 70. That is, the history of abnormal occurrences in the residual vibration data of the nozzle block, including the nozzle 227 with the discharge abnormality, is stored in the determination result holding unit 72.

[0081] After step S58, steps S60 to S66 are performed. In steps S60 to S66, similar to steps S40 to S46 in Figure 10, nozzles 227 with discharge abnormalities are detected among the multiple nozzles 227 included in the nozzle block in which an abnormality in residual vibration data was detected. The operation from steps S60 to S66 is repeated for the number of nozzles 227 included in the nozzle block in which an abnormality in residual vibration data was detected. The operation from steps S60 to S66 is an example of the second operation.

[0082] First, in step S60, the drive control unit 10 applies a drive voltage to a piezoelectric element 30 corresponding to one of the multiple nozzles 227 included in the nozzle block in which an abnormality in residual vibration data was detected. The selection unit 40 acquires the residual vibration voltage generated in accordance with the drive voltage applied to the piezoelectric element 30 corresponding to one of the nozzles 227 in the nozzle block in which an abnormality in residual vibration data was detected, and generates residual vibration data.

[0083] Next, in step S62, the comparison unit 50 compares the residual vibration data generated by the selection unit 40 with a reference value for detecting discharge abnormalities in the nozzle 227 and outputs the comparison result as difference data to the determination unit 60. Next, in step S64, the determination unit 60 detects nozzles 227 with abnormal residual vibration data (i.e., residual vibration waveform and residual vibration voltage) based on the difference data as nozzles 227 with discharge abnormalities. Next, in step S66, the determination unit 60 stores information indicating the nozzle 227 that has been detected to have a discharge abnormality as a determination result in the determination result holding unit 72 of the data holding unit 70. That is, the occurrence history of nozzles 227 that have experienced discharge abnormalities is stored in the determination result holding unit 72. Then, since nozzles 227 with discharge abnormalities have been detected, the operation shown in Figure 11 is terminated.

[0084] As described above, in the second embodiment as well, if a discharge abnormality is detected in any of the multiple nozzle blocks included in a single nozzle row, the determination time for determining whether or not a nozzle 227 has a discharge abnormality can be shortened by detecting the nozzle 227 with the discharge abnormality from among the multiple nozzles 227 included in the nozzle block in which the discharge abnormality was detected.

[0085] Furthermore, in the second embodiment, information indicating the nozzle block in which an abnormality in residual vibration data was detected is stored in the determination result holding unit 72. When an abnormality is found in the residual vibration data of a nozzle block with a high frequency of occurrence of abnormal residual vibration data, a nozzle 227 with a discharge abnormality is detected from the nozzle block with the abnormality. Nozzles 227 in which a discharge abnormality has been detected in the past may be more prone to recurring discharge abnormalities compared to other nozzles 227. By determining which nozzle blocks to detect abnormalities in residual vibration data according to the frequency of abnormality occurrence, nozzles 227 with discharge abnormalities can be efficiently detected, and the determination time for determining whether or not a nozzle 227 has a discharge abnormality can be further shortened.

[0086] Furthermore, in the second embodiment, if there is no abnormality in the nozzle block where the frequency of abnormal residual vibration data occurrence is high, the nozzle row including the nozzle block where the frequency of abnormalities is low is subjected to an abnormal residual vibration data detection operation (Figure 10). By detecting abnormal residual vibration data from the nozzle block where the frequency of abnormalities is high, the probability of detecting an abnormal residual vibration data in step S26 of Figure 10 can be reduced compared to the case where the abnormality detection operation for the nozzle block where the frequency of abnormalities is high is not performed. Therefore, the probability of performing the operations from step S28 onward in Figure 10 can be reduced, and the determination time for determining whether or not there is a discharge abnormality in the nozzle 227 can be shortened.

[0087] (Hardware configuration of inkjet recording head) Figure 12 is a block diagram showing an example of the hardware configuration of the inkjet recording head 220 shown in Figure 4. The inkjet recording head 220 includes a CPU 201, a ROM (Read Only Memory) 202, and a RAM (Random Access Memory) 203. The inkjet recording head 220 also includes an input interface unit 204, an output interface unit 205, an input / output interface unit 206, and a communication interface unit 207.

[0088] For example, the CPU 201, ROM 202, RAM 203, input interface unit 204, output interface unit 205, input / output interface unit 206, and communication interface unit 207 are interconnected via a bus.

[0089] The CPU 201 executes various programs such as the OS (Operating System) and applications. The ROM 202 holds basic programs and various parameters that enable the CPU 201 to execute these programs. The RAM 203 stores the various programs executed by the CPU 201 and the data used by these programs. For example, the functions of the comparison unit 50 and the determination unit 60 in Figure 4 may be realized by various programs.

[0090] The input interface unit 204 and the output interface unit 205 are connected to the controller 211. For example, an input / output device 240 such as an HDD (Hard Disk Drive) and recording medium (not shown) is connected to the input / output interface unit 206. Note that the inkjet recording head 220 does not necessarily have an input / output interface unit 206.

[0091] If the recording medium stores various programs, such as a control program for controlling the operation of the inkjet recording head 220 or an abnormality detection program for detecting nozzle ejection abnormalities based on residual vibration waveforms, the programs are transferred from the recording medium to the RAM 203 or the like via the input / output interface unit 206. The communication interface unit 207 allows the inkjet recording head 220 to be connected to a network or the like, in which case the various programs may be downloaded from the network via the communication interface unit 207.

[0092] Examples of the present invention are as follows: <1> Multiple piezoelectric elements that apply pressure to multiple discharge sections, each containing a nozzle for discharging liquid, Multiple voltage lines connected to each of the aforementioned multiple piezoelectric elements, A drive unit that applies a drive voltage to each of the plurality of piezoelectric elements via the plurality of voltage lines, A selection unit that selects one or more voltage lines after applying a driving voltage to the plurality of piezoelectric elements and generates residual vibration data based on the sum of residual vibration voltages due to residual vibration appearing on the selected voltage lines, An abnormality determination unit determines an abnormality in residual vibration data by comparing the residual vibration data generated by the selection unit with a reference value for determining abnormalities in residual vibration, The system includes a control unit that detects a discharge unit having a discharge abnormality based on the determination result by the abnormality determination unit, The control unit, A first operation in which the drive unit simultaneously applies a drive voltage to a group of interest, which is one of a plurality of groups each containing a predetermined number of piezoelectric elements, the selection unit simultaneously selects a plurality of voltage lines corresponding to the group of interest, and if the abnormality determination unit determines that there is an abnormality in the residual vibration data appearing on the selected plurality of voltage lines, it detects that there is a discharge abnormality in one of the plurality of discharge units corresponding to the group of interest, If a discharge abnormality is detected in the first operation, the drive unit sequentially applies a drive voltage to a plurality of piezoelectric elements within the group of interest, the selection unit sequentially selects the voltage lines to which the drive voltage has been applied, and the selection unit detects that there is a discharge abnormality in the discharge section corresponding to the piezoelectric element for which an abnormality in residual vibration data has been determined. A liquid dispensing device characterized by the following. <2> Before performing the first operation, the control unit performs a third operation in which it simultaneously applies a drive voltage to the piezoelectric elements of multiple groups using the drive unit, simultaneously selects multiple voltage lines corresponding to the multiple groups using the selection unit, and determines whether there is an abnormality in the residual vibration data appearing on the selected multiple voltage lines. If an abnormality in the residual vibration data is determined in the third operation, the control unit sequentially performs the first operation on each of the multiple groups as the group of interest. Characterized by <1> The liquid dispensing device described above. <3> The control unit causes the reference value used by the abnormality determination unit to be different for the first operation, the second operation, and the third operation. Characterized by <2> The liquid dispensing device described above. <4> If the abnormality determination unit determines that the residual vibration data is abnormal, it stores the determination result in the holding unit. The control unit performs a fourth operation based on the determination result stored in the holding unit, which involves simultaneously applying a drive voltage to the high-frequency group, the group in which the frequency of occurrence of abnormal residual vibration data is higher than the reference frequency, simultaneously selecting a plurality of voltage lines corresponding to the high-frequency group using the selection unit, and having the abnormality determination unit determine whether or not there is an abnormality in the residual vibration data appearing on the plurality of selected voltage lines. If an abnormality in the residual vibration data is determined in the fourth operation, the control unit performs the second operation. Characterized by <3> The liquid dispensing device described above. <5> If the control unit does not determine an abnormality in the residual vibration data in the fourth operation, it performs the third operation. Characterized by <4> The liquid dispensing device described above. <6> The device has a plurality of first switches that connect the drive unit to the plurality of voltage lines, The control unit turns off the first switch connected to the voltage line selected by the selection unit. Characterized by <1> or <5> A liquid dispensing device as described in any one of the items. <7> The system includes at least one of the following: a first acquisition unit that smooths the waveform of residual vibration data to acquire smoothed data; a second acquisition unit that acquires the peak value of the waveform of residual vibration data; and a third acquisition unit that acquires the phase or period in which the peak value of the waveform of residual vibration data appears. The control unit operates one of the first acquisition unit, the second acquisition unit, or the third acquisition unit, and causes the abnormality determination unit to determine a discharge abnormality based on the reference value corresponding to the operated acquisition unit. Characterized by <1> or <6> A liquid dispensing device as described in any one of the items. <8> A control method for a liquid dispensing device comprising: a plurality of piezoelectric elements that apply pressure to a plurality of dispensing sections, each including a nozzle for dispensing liquid; a plurality of voltage lines connected to each of the plurality of piezoelectric elements; and a drive unit that applies a drive voltage to each of the plurality of piezoelectric elements via the plurality of voltage lines, The selection unit of the liquid dispensing device selects one or more voltage lines after applying a drive voltage to the plurality of piezoelectric elements, and generates residual vibration data based on the sum of residual vibration voltages due to residual vibration appearing on the selected voltage lines. The abnormality determination unit of the liquid dispensing device determines whether there is an abnormality in the residual vibration data by comparing the residual vibration data generated by the selection unit with a reference value for determining the abnormality of residual vibration. The control unit of the liquid dispensing device detects the dispensing unit having a dispensing abnormality based on the determination result by the abnormality determination unit, The control unit, A first operation in which the drive unit simultaneously applies a drive voltage to a group of interest, which is one of a plurality of groups each containing a predetermined number of piezoelectric elements, the selection unit simultaneously selects a plurality of voltage lines corresponding to the group of interest, and if the abnormality determination unit determines that there is an abnormality in the residual vibration data appearing on the selected plurality of voltage lines, it detects that there is a discharge abnormality in one of the plurality of discharge units corresponding to the group of interest, If a discharge abnormality is detected in the first operation, the drive unit sequentially applies a drive voltage to a plurality of piezoelectric elements within the group of interest, the selection unit sequentially selects the voltage lines to which the drive voltage has been applied, and the selection unit detects that there is a discharge abnormality in the discharge section corresponding to the piezoelectric element for which an abnormality in residual vibration data has been determined. A control method for a liquid dispensing device characterized by the following.

[0093] Although the present invention has been described above based on various embodiments, the present invention is not limited to the requirements shown in the above embodiments. These points can be modified as long as they do not impair the spirit of the present invention, and can be appropriately determined according to their application. [Explanation of Symbols]

[0094] 10 Drive control unit 20 Drive unit 30 Piezoelectric elements 40 Selection Section 41 Smooth section 42 Peak detection unit 43 Phase detection unit 50 Comparison Section 51, 52, 53 Difference generation part 60 Judgment section 70 Data storage unit 71 Reference value holding section 72 Judgment result holding section 100 Inkjet Recording Devices 101 Recording means 102 Platen 103 Drying means 104 Regulatory Guide 105 Infeed section 106 Dansarola 107 EPC 108 Meandering Amount Detector 109 Outfeed section 110 Pla 111 Recording medium supply unit 112 Recording Media Recovery Unit 113 Recording media 114 Maintenance and recovery means 204 Input Interface Section 205 Output Interface Section 206 Input / Output Interface Section 207 Communication Interface Section 210 Drive control board 211 Controller 212 Drive waveform generation unit 213 Memory means 220 inkjet recording heads 221 Head board 222 Residual vibration detection substrate 223 Head drive IC board 224 Ink Tanks 225 Rigid Plate 226 Nozzle Plate 227 Nozzles 230 Cable 231 Drive control board side connector 232 Head-side connector 240 Input / Output Devices BUS DRV Driver T Dispensing cycle Vp-p voltage amplitude [Prior art documents] [Patent Documents]

[0095] [Patent Document 1] Patent No. 4114638 [Patent Document 2] Japanese Patent Publication No. 2017-039256

Claims

1. Multiple piezoelectric elements that apply pressure to multiple discharge sections, each containing a nozzle for discharging liquid, Multiple voltage lines connected to each of the aforementioned multiple piezoelectric elements, A drive unit that applies a drive voltage to each of the plurality of piezoelectric elements via the plurality of voltage lines, A selection unit that selects one or more voltage lines after applying a driving voltage to the plurality of piezoelectric elements, and generates residual vibration data based on the sum of residual vibration voltages due to residual vibration appearing on the selected voltage lines, An abnormality determination unit determines an abnormality in residual vibration data by comparing the residual vibration data generated by the selection unit with a reference value for determining abnormalities in residual vibration, The system includes a control unit that detects a discharge unit having a discharge abnormality based on the determination result by the abnormality determination unit, The control unit, A first operation in which the drive unit simultaneously applies a drive voltage to a group of interest, which is one of a plurality of groups each containing a predetermined number of piezoelectric elements, the selection unit simultaneously selects a plurality of voltage lines corresponding to the group of interest, and if the abnormality determination unit determines that there is an abnormality in the residual vibration data appearing on the selected plurality of voltage lines, it is detected that there is a discharge abnormality in one of the plurality of discharge units corresponding to the group of interest, If a discharge abnormality is detected in the first operation, the drive unit sequentially applies a drive voltage to a plurality of piezoelectric elements within the group of interest, the selection unit sequentially selects the voltage lines to which the drive voltage has been applied, and the selection unit detects that there is a discharge abnormality in the discharge section corresponding to the piezoelectric element for which an abnormality in residual vibration data has been determined. A liquid dispensing device characterized by the following.

2. Before performing the first operation, the control unit performs a third operation in which it simultaneously applies a drive voltage to the piezoelectric elements of the multiple groups using the drive unit, simultaneously selects the multiple voltage lines corresponding to the multiple groups using the selection unit, and determines whether there is an abnormality in the residual vibration data appearing on the selected multiple voltage lines. If an abnormality in the residual vibration data is determined in the third operation, the control unit sequentially performs the first operation on each of the multiple groups as the group of interest. A liquid dispensing device according to claim 1, characterized by the following:

3. The control unit causes the reference value used by the abnormality determination unit to be different for the first operation, the second operation, and the third operation. The liquid dispensing device according to claim 2, characterized by the following:

4. If the abnormality determination unit determines that the residual vibration data is abnormal, it stores the determination result in the holding unit. The control unit performs a fourth operation based on the determination result stored in the holding unit, which involves simultaneously applying a drive voltage to the high-frequency group, which is the group in which the frequency of occurrence of abnormal residual vibration data is higher than the reference frequency, simultaneously selecting a plurality of voltage lines corresponding to the high-frequency group using the selection unit, and having the abnormality determination unit determine whether or not there is an abnormality in the residual vibration data appearing on the plurality of selected voltage lines. If an abnormality in the residual vibration data is determined in the fourth operation, the control unit performs the second operation. The liquid dispensing device according to claim 3, characterized by the following:

5. If the control unit does not determine an abnormality in the residual vibration data in the fourth operation, it performs the third operation. A liquid dispensing device according to claim 4, characterized by the following:

6. The device has a plurality of first switches that connect the drive unit to the plurality of voltage lines, The control unit turns off the first switch connected to the voltage line selected by the selection unit. A liquid dispensing device according to any one of claims 1 to 5, characterized by the above.

7. The system includes at least one of the following: a first acquisition unit that smooths the waveform of residual vibration data to acquire smoothed data; a second acquisition unit that acquires the peak value of the waveform of residual vibration data; and a third acquisition unit that acquires the phase or period in which the peak value of the waveform of residual vibration data appears. The control unit operates one of the first acquisition unit, the second acquisition unit, or the third acquisition unit, and causes the abnormality determination unit to determine a discharge abnormality based on the reference value corresponding to the operated acquisition unit. A liquid dispensing device according to any one of claims 1 to 5, characterized by the above.

8. A control method for a liquid dispensing device comprising: a plurality of piezoelectric elements that apply pressure to a plurality of dispensing sections, each including a nozzle for dispensing liquid; a plurality of voltage lines connected to each of the plurality of piezoelectric elements; and a drive unit that applies a drive voltage to each of the plurality of piezoelectric elements via the plurality of voltage lines, The selection unit of the liquid dispensing device selects one or more voltage lines after applying a driving voltage to the plurality of piezoelectric elements, and generates residual vibration data based on the sum of residual vibration voltages due to residual vibration appearing on the selected voltage lines. The abnormality detection unit of the liquid dispensing device determines whether there is an abnormality in the residual vibration data by comparing the residual vibration data generated by the selection unit with a reference value for determining the abnormality of residual vibration. The control unit of the liquid dispensing device detects the dispensing unit having a dispensing abnormality based on the determination result by the abnormality determination unit, The control unit, A first operation in which the drive unit simultaneously applies a drive voltage to a group of interest, which is one of a plurality of groups each containing a predetermined number of piezoelectric elements, the selection unit simultaneously selects a plurality of voltage lines corresponding to the group of interest, and if the abnormality determination unit determines that there is an abnormality in the residual vibration data appearing on the selected plurality of voltage lines, it is detected that there is a discharge abnormality in one of the plurality of discharge units corresponding to the group of interest, If a discharge abnormality is detected in the first operation, the drive unit sequentially applies a drive voltage to a plurality of piezoelectric elements within the group of interest, the selection unit sequentially selects the voltage lines to which the drive voltage has been applied, and the selection unit detects that there is a discharge abnormality in the discharge section corresponding to the piezoelectric element for which an abnormality in residual vibration data has been determined. A control method for a liquid dispensing device characterized by the following.

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